Process for purifying hydrocarbon oils



atented Aug. i2, 1930 STATES mo rnnsz, or mnnsnunn, ennmm raocnss nonromaine mnocannon one 80 Drawing. Application filed Ju1y,8, .1924,Serial No. 724,792, and in Germany July 18, 1928.

This invention relates to the processes for purifying hydrocarbon oils,such as petroleum, shale oil, brown coal tar oil, pit coal tar oil, andthe products obtained therefrom.

5 It is known that hydrocarbon oils which have only been distilled inthe manner usual in the art, after some time assume a dark colour and insome cases a disagreeable odour and that there is aformation of resinand a separation of a deposit.

In order to avoid these objectionable phenomena, the oils are, afterdistillation, subjected to a refining process.

'- Now I have found that these objectionable phenomena are not caused bythe hydrocarbons themselves, but by certain com ounds present in theseoils and. containing esides carbon and hydrogen, also oxygen, nitrogenand sulfur. Such compounds are especially oxygen-containing bodies, suchas furaneand its homologues, and nitrogen-containing bodies, such aspyrrol and its homologues, and derivatives of these-compounds.

In the usual refining processes for instance when refining thehydrocarbons by treatment with sulfuric acid, not onlytheseobjectionable constituents are acted upon and removed, but also theolefines, though there would be no objection to leaving them in the oil.This,

of course, causes a loss of valuable material, which loss is especiallyremarkable in the case of oils containing a large percentage ofunsaturated constituents, such oils being obtained for instance bydestructive distillation of brown coal or lignite and by the knowncrackingprocesses.

Now, I have further found that the constit-uents, causing the darkcoloration or the disagreeable odour or the formation of resins anddeposits, have a well defined boiling temperature, depending upon thenature of the oils, and that consequently these constituents can beseparated and removed by fractional distillation, if this is veryexactly performed.- According to my invention, I proceed incontradiction to the distillation processes usual in the treatment ofmineral oils. In-

deed, in distilling mineral oils, it is now usual toseparate the oilsinto fractions boilinig within relatively large limits, while accornarrow boiling tageous to effect the distillation under reduced ing tomy invention, the distillation is performed in apparatus allowing offractions being obtained which distil over within very limits, thefractions being preferably col ected separately from degree to degree oreven less. Such apparatus are for instance known and used in the artofrectifying alcohol. By applying this method,

it is possible, by separately collecting the products which aredistilled within such narrow limits, to ascertain first by a preliminarytest, which fractions of the material under treatment contain theobjectionable constituents, which fractions may be, termed resin formingfractions. These fractions are removed when distilling the oils inraetice, while the other fractions not containing such constituents maybe collected within any convenient limits. It is therefore possible torefine the oils by a simple exact fractional distillation and to avoid"artly orwholly the usual refining probesses y'means of chemicalsubstances and the losses connected there with. As the boiling points ofthe resin forming substances depend upon the pressure, itis advisable tokeep the pressure constant during the distillation.

In certain cases, especially in the case of oils having a high boilingpoint, it isadvamso pressure, as the boiling points of the, resin ormingsubstances are modified by a change of pressure. Thus, it is possible inmany cases to prevent other substances which at a certain pressure wouldbe distilled over at the same temperature as the resin forming.substances, from being removed together with the latter, the boilingpoint of'such substances being modified in another manner than that ofthe resin forming substances, if the pressure is changed.

In certain cases it is also possible to a ply reduced pressure onlyduring a part 0 the distillation.

Similar methods can be applied to-the further treatment of the separatedresin forming fractions.

In certain cases the urification can be ob tained more rapidly, y firstformin fractions boiling within somewhat larger imits, 10

comprising morethan one degree, and then removing the resin formingconstituents by subjecting these fractions to a further exact fractionaldistillation as described.

The raw materials can either be immediately treated as described, orfirst be subjected to a slight preliminary refining treatgravity, isdistilled by means of a rectifyin ment as usual in the art of treatingpetro- Ewampl'es 1. Benzine, obtained by destructive distillation ofbrown coal and having 0,780 specific apparatus provided with anefficient dephlegmator, and the distilled products are separatelycollected fromdegree to degree. It is found that the fractionsdistilling over at 62, 86 and 108 C. contain colouring, resin form ingand deposit forming eonstltuents, while theother fractions do notcontain such substances. It is therefore possible to obtain a pureproduct, not .c'ontamin objectionable constituents by simply distillingthe said oil and removing the fractions above referred to. Otherstarting materials can be treated in an analogous manner. 2. Whendistilling a brown coal benzijne having a resin forming fractionboiling'at 138 C. and containing a remarkable percentage of xylols, most'of these xylols is distilled over together with the said resin formingfraction. If, however, the distillation is effected under reducedpressure, for

' loss of xylol-being avoided.

. fractions, which have been separated, can be 3. In thecase referred toin Example 2 it is also possible to perform the distillation first atordinary pressure, the pressure being kept constant until a temperatureof 125 C. is reached, and then to apply reduced pressure. By proceedingin this manner, the

boiling oint of the res1n forming fractions is modi ed in another mannerthan that of the hydrocarbons boiling at'theisame temperature atordinary pressure, and the same result is obtained .as in Example 2. a

In a similar manner the resin forming further treated.

at I claim is 1. The process for purifying hydrocarbon oils, which comrises separating a test portion from the oil distilling said portion andcollecting therefrom fractions within narrow limits to determine theboiling temperatures of fractions forming resins and deposits andcausing coloration and disagreeable odors, then distilling the main bodyof the oil fractionally and at the ascertained temperatures, andseparating such fractions from the remainder of the oil. 7

. 2. The process for purifying hydrocarbon oils contalning a largepercentage of unsaturated hydrocarbons and olefines, which comprisesseparating a test portion from the oil, distilling said portion andcollecting therefrom fractions within narrow limits to determine theboiling temperatures of fractions forming resins and deposits andcausing colg oration and disagreeable odors, 'then distilling the mainbody of the oil 'fractionally and without substantial loss of olefinesand at the ascertained temperatures, and separating such fractions fromthe remainder of the oil.

3. The process for purifying hydrocarbon oils, which comprisesseparating a test portion from the oil, distilling said portion andcollecting therefrom fractions within narrow limits to determine the.boiling temperatures of fractions forming resins and deposits andcausing coloration and disagreeable odors,

then distilling the main body of the oil fractionally and at theascertained temperatures, and separating and discarding such fractionsfrom the remainder of the oil.

4. The process for purifying hydrocarbon oils, which comprisesseparating a test portion from the oil, distilling said portion andcollecting therefrom fractions within narrow limits to determine theboiling temperatures of fractions forming resins and deposits andcausing coloration and disagreeable odors, then distilling the main bodyof the oil fractionallv and at the ascertained temperatures, separatingsuch fractions from the remainder of the oil, and completing thefractional distillation of the oil. and blending said fractions.

5. The process for purifying hydrocarbon oils, which comprisesseparating a test portion from the oil, distilling said portion andcollecting therefrom fractions within narrow limits to determine theboiling temperatures pf fractions forming resins and deposits andcausing coloration and disagreeable odors, then distilling underconstant pressure the main body of the oil fractionally and at theascertained temperatures, and separating such fractions from theremainder of the oil.

6. 'The process for purifying hydrocarbon oils, which comprisesseparating a test portion from the oil, distilling said portion andcollecting therefrom fractions within narrow limits to determinetheboiling temperatures of fractions forming resins and deposits andcausing coloration and disagreeable odors, then distilling under reducedconstant pressure the main body of the oil fractionally and at theascertained temperatures, and separatcausing l 0 ing such fractions fromthe remainder of the o1 7. The rocess for purifying hydrocarbon oils,whic comprises separating a test portion from the oil, distilling saidportion and collecting therefrom fractions within narrow limits todetermine the boiling temperatures of fractions forming resins anddegosits and coloration and disagreea 1e odors,

then distillingthe main body of the oil fractionally', distllling theseparated fractions under reduced constant pressure and at theascertained temperatures, and separatmg such fractions from theremainder of the oil.

In testimony vi -hereof I have afiixed my ,JENo mn's z.

